Help identifying part

We have a sunroom that was already part of the house when we acquired it in 2004. The very small rollers on the bottom of the windows have been broken over time.

I've removed one of the unbroken rollers in order to photograph it (see attached).

Measurements are:

3/4" long
Inner track width approx. 3/16"

You can see a pin on the side that faces up; this goes into a hole on the window and thereby holds the roller in place.


Here are a few photos. Note that the wheel is "loose" inside the bracket and is held in by tension when in place. The wheel is not concave or convex.

The bracket is 3/4" long, 5/16" deep (not including the pin that sticks into the frame).

At the widest part, the frame is 1/4" wide. The thinner part that goes into the track in the frame is 1/8" wide.

The wheel has a diameter of 5/16".